Substituting whole grains for refined grains in a 6-wk randomized trial has a modest effect on gut microbiota and immune and inflammatory markers of healthy adults

• Published in: The American journal of clinical nutrition Vol. 105; no. 3; pp. 635 - 650
• Main Authors: Vanegas, Sally M, Meydani, Mohsen, Barnett, Junaidah B, Goldin, Barry, Kane, Anne, Rasmussen, Helen, Brown, Carrie, Vangay, Pajau, Knights, Dan, Jonnalagadda, Satya, Koecher, Katie, Karl, J Philip, Thomas, Michael, Dolnikowski, Gregory, Li, Lijun, Saltzman, Edward, Wu, Dayong, Meydani, Simin Nikbin
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Nutrition, Inc 01.03.2017; American Society for Nutrition
• Subjects: acetates; Acetic Acid - metabolism; Adults; Aged; Bacteria - growth & development; Bacteria - metabolism; Biomarkers; Biomarkers - metabolism; body mass index; body weight; Body Weight Maintenance; butyrates; Butyrates - metabolism; cell-mediated immunity; Clinical trials; Defecation; Diet; Dietary Fiber - pharmacology; Digestive system; Enterobacteriaceae; Enterobacteriaceae - growth & development; Enterobacteriaceae - metabolism; Feces; Feeding Behavior; Female; Gastrointestinal Microbiome; Gastrointestinal Tract - immunology; Gastrointestinal Tract - metabolism; Gastrointestinal Tract - microbiology; Grain; Humans; Immunity; Immunity, Innate; inflammation; Inflammation - metabolism; Inflammation - microbiology; innate immunity; intestinal microorganisms; Lachnospira; Lipopolysaccharides; Male; men; Microorganisms; Middle Aged; observational studies; postmenopause; refined grains; Resorcinols - blood; short chain fatty acids; T-lymphocytes; T-Lymphocytes - metabolism; tumor necrosis factor-alpha; Tumor Necrosis Factor-alpha - metabolism; Western diets; whole grain foods; Whole Grains; women; whole grains; healthy adults; immune; inflammation; gut microbiota
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.3945/ajcn.116.146928

Observational studies suggest an inverse association between whole-grain (WG) consumption and inflammation. However, evidence from interventional studies is limited, and few studies have included measurements of cell-mediated immunity. We assessed the effects of diets rich in WGs compared with refined grains (RGs) on immune and inflammatory responses, gut microbiota, and microbial products in healthy adults while maintaining subject body weights. After a 2-wk provided-food run-in period of consuming a Western-style diet, 49 men and 32 postmenopausal women [age range: 40-65 y, body mass index (in kg/m ) <35] were assigned to consume 1 of 2 provided-food weight-maintenance diets for 6 wk. Compared with the RG group, the WG group had increased plasma total alkyresorcinols (a measure of WG intake) ( < 0.0001), stool weight ( < 0.0001), stool frequency ( = 0.02), and short-chain fatty acid (SCFA) producer [false-discovery rate (FDR)-corrected = 0.25] but decreased pro-inflammatory (FDR-corrected = 0.25). Changes in stool acetate ( = 0.02) and total SCFAs ( = 0.05) were higher in the WG group than in the RG group. A positive association was shown between and acetate (FDR-corrected = 0.002) or butyrate (FDR-corrected = 0.005). We also showed that there was a higher percentage of terminal effector memory T cells ( = 0.03) and LPS-stimulated ex vivo production of tumor necrosis factor-α ( = 0.04) in the WG group than in the RG group, which were positively associated with plasma alkylresorcinol concentrations. The short-term consumption of WGs in a weight-maintenance diet increases stool weight and frequency and has modest positive effects on gut microbiota, SCFAs, effector memory T cells, and the acute innate immune response and no effect on other markers of cell-mediated immunity or systemic and gut inflammation. This trial was registered at clinicaltrials.gov as NCT01902394.